Due to higher speeds and more agile movements, *UAVs need fast, light and energy-efficient solutions for robust obstacle avoidance.
Systems relying on a single camera typically use optical flow information, computed between two consecutive frames to perceive the structure of the environment.
The main advantage of such structure-from-motion approaches is that they are lightweight and energy-efficient and can therefore be used for small *UAVs.
[1]} proposed a probabilistic method of computing the optical flow for more robust obstacle detection.
[2]} used a data driven optical flow approach learning the flight behaviour from a human expert.
Nonetheless, since the information gained by a single camera system is limited, such systems are typically infeasible for robot navigation.
